1. Field of the Invention
This invention relates to a multi-layer recording medium reproducing device adapted to reproduce, for instance, a multi-layer optical recording medium, and more particularly to a multi-layer recording medium reproducing device having an automatic adjustment mode of automatically carrying out servo adjustment (adjustment of focusing servo and tracking servo) to satisfactorily reproduce a multi-layer optical recording medium.
2. Description of the Related Art
An optical disk recording and reproducing device has been proposed in the art which uses an optical recording medium (hereinafter referred to as xe2x80x9can optical diskxe2x80x9d, when applicable) such as a digital video disk (DVD) to record or reproduce data.
The optical disk recording and reproducing device has an optical pick-up made up of a variety of optical components. The laser beam of the optical pick-up, while being converged on the pit surface of the optical disk, is moved radially outwardly on the optical disk, to read signals recorded on the optical disk.
In this case, in order that the focusing servo of converging the laser beam of the optical pick-up on the pit surface of the optical disk and the tracking servo of radially moving the optical pick-up along the recording track of the optical disk are carried out with high accuracy, it is necessary to adjust in advance the offset, gain and balance of the focusing servo and tracking servo.
The adjustment of the offset, gain and balance of the focusing servo and tracking servo (hereinafter referred to as xe2x80x9ca servo adjustmentxe2x80x9d, when applicable) is heretofore manually achieved. More specifically, an optical disk is loaded on the optical disk recording and reproducing device. While the optical disk is being reproduced for a predetermined period of time, for instance, the resistance values of pre-set resistors provided in the focusing servo circuit and in the tracking servo circuit are adjusted.
However, a recent optical disk recording and reproducing device has an automatic adjustment mode of automatically performing the focusing and tracking servo adjustment. That is, when the user loads an optical disk on the optical disk recording and reproducing device, and operates a reproducing button, immediately after the reproduction starts the automatic adjustment mode is carried out for a predetermined period of time (of the order of 5 to 10 sec) . That is, the servo adjustment is automatically performed. When the focusing servo and the tracking servo become satisfactory, the initial state is effected again, to actually start the reproduction of the optical disk.
On the other hand, recently an optical disk has been greatly increased in capacity. Accordingly, the structure of the optical disk has been changed from a single-layer structure to a multi-layer structure (mainly a double-layer structure).
In the multi-layer optical disk, different layers have different servo adjustment values. Therefore, whenever a recording layer to be reproduced is switched, it is necessary to perform the servo readjustment.
For instance when, with a multi-layer optical disk loaded on the optical disk recording and reproducing device, during the reproduction of the first layer (the front layer) the operator operates the button to switch, the first layer is switched over to the second layer (the layer under the first layer), at this time instant the optical disk recording and reproducing device performs the automatic adjustment mode, and, after the servo readjustment, starts the reproduction of the second layer.
That is, in the conventional optical disk recording and reproducing device, whenever the recording layer to be reproduced is switched (i.e., whenever the first layer is switched over to the second layer or the second layer is switched over to the first layer) the automatic adjustment mode must be performed for about five to ten seconds. Therefore, the switching of the recording layers is not smoothly achieved. During this period, nothing is reproduced (i.e., no sound is produced), and therefore the user is struck as incongruity and feels uncomfortable.
In view of the foregoing, an object of the invention is to provide a multi-layer recording medium reproducing device in which, even if the recording layer to be reproduced is switched during the reproduction of a multi-layer optical disk, the switching operation is achieved smoothly.
In order to achieve the above object, the invention provides a multi-layer recording medium reproducing device having an automatic adjustment mode of automatically performing servo adjustment to reproduce a multi-layer recording medium, the device comprising: a storing section which, during the automatic adjustment mode, performs the servo adjustment of recording layers of the multi-layer recording medium respectively for predetermined periods of time, and stores the resultant servo adjustment values respectively for the recording layers; and a servo adjustment control section which, during a reproduction of the multi-layer recording medium, reads from the storing section a servo adjustment value corresponding to one of the recording layers to be reproduced, and performs the servo adjustment to reach the servo adjustment value thus read.